This blog continues the discussion that we began with Epic Journey: The 2008 Elections and American Politics (Rowman and Littlefield, 2009).The latest book in this series is Defying the Odds: the 2016 Elections and American Politics.

One way of looking at the House results is by the population density of congressional districts. CityLab places congressional districts on a continuum of six categories, ranging from “pure rural” to “pure urban.” In between are four categories of suburban districts, from less dense to more dense.

The CityLab Congressional Density Index.

Take the 11 most rural districts that were on the competitive lists assembled by the Cook Political Report ahead of the election. Going into the election, Republicans held nine of the 11. When the new Congress assembles in January, they will still hold eight of the 11.

GOP losses in the next category, what are called suburban-rural districts, were also modest. Seven of 19 districts in this group changed parties: five shifting to the Democrats and two to the Republicans. Republicans had 17 of these districts going into the election and will end up with either 13 or 14 in the new Congress.

But the damage grows exponentially in the next two categories. There were 30 districts categorized as suburban-sparse. Heading into the election, Republicans held every one of them. As a result of the election, Democrats will have 16 to the GOP’s 14.

In the 15 districts described as suburban-dense, something similar happened. Republicans held all 15 before the election. In January, they will have control of just three. In the nine districts categorized as urban-suburban, Republicans will go from holding seven to holding just one.

Democrats made big gains in 12 districts held by Republicans that were won by Hillary Clinton in 2016 and Barack Obama in 2012, flipping nine of them. In another 13 districts won by Clinton in 2016 and by Mitt Romney in 2012, Democrats flipped another 12.Democrats also converted eight of 12 districts that Trump won in 2016 but that Obama had won in 2012. Republicans did better in the districts won by Trump in 2016 and Romney in 2012, which constituted more than half of all the competitive districts, but Democrats still managed to convert nearly a third of them.

California delivered the most significant blow to the Republicans. The party there has been in a long decline, and Trump’s presidency has made things worse. Democrats will pick up at least six seats in California, with a seventh possible. The lone competitive seat that remained in GOP hands was that of Rep. Duncan D. Hunter, who is under indictment on allegations of making personal use of campaign funds.